External SIXX persistance exists.
I haven't looked at it yet, but I am skeptical. Do you think
it will do what I want? XML is just barely human readable.
It tends to be slow. It is OK for a least common denominator,
but you can almost always do better.
I've looked at the mailing list. I didn't read the whole thing,
though, and I probably didn't understand a lot that I read.